edeliver_fork v1.4.6 Edeliver.Relup.Instructions.CheckRanchConnections
This upgrade instruction checks whether the running ranch connections can be found.
This instruction will cause the upgrade to be canceled if the ranch connections cannot be found and because it is insterted before the “point of no return” it will run twice, once when checking the relup and once when executing the relup.
If Phoenix.PubSub.PG2
is used as pubsub backend for phoenix channels,
running websocket processes will be detected and suspended by the
Edeliver.Relup.Instructions.SuspendChannels
instruction during the upgrade and resumed by the
Edeliver.Relup.Instructions.ResumeChannels
instruction
after the upgrade / downgrade of the node.
Link to this section Summary
Functions
Returns name of the application
Calls the run/1
function of this module
This module requires the Edeliver.Relup.Instructions.CheckRanchAcceptors
module
Inserts the instruction before the point of no return
Modifies the relup file
Gets the process ids of the ranch socket connections if there are any
Gets the pid of the supervisor which supervises the ranch connections
Checks whether the ranch connections can be found
Returns the pids of the connections which are websocket connections for channels
Link to this section Functions
Returns name of the application.
This name is taken as argument for the run/1
function
and is required to access the acceptor processes through the supervision tree
call_this(arguments :: [term()]) :: Instruction.instruction() | Instruction.instructions()
Calls the run/1
function of this module
from the relup file during hot code upgrade
dependencies() :: [instruction_module :: atom()]
dependencies() :: [Edeliver.Relup.Instructions.CheckRanchAcceptors]
This module requires the Edeliver.Relup.Instructions.CheckRanchAcceptors
module
which must be loaded before this instruction for upgrades and unload after this instruction for downgrades.
Inserts the instruction before the point of no return.
This causes the release handler to abort the upgrade
already when running :release_handler.check_install_release/1
if this instruction fails.
Modifies the relup file.
Modifies the relup
file which will be used to upgrade (or downgrade) from one version to another
by inserting, removing, or shifting appup instructions.
See Edeliver.Relup.InsertInstruction
and Edeliver.Relup.ShiftInstruction
for useful helpers to
insert / position the instructions and Edeliver.Relup.RunnableInstruction
to execute custom code
during the upgrade.
Callback implementation for Edeliver.Relup.Instruction.modify_relup/2
.
ranch_connections(ranch_acceptors_sup :: pid()) :: [:supervisor.child_id()]
Gets the process ids of the ranch socket connections if there are any.
Gets the pid of the supervisor which supervises the ranch connections.
If it cannot be found as child of the given ranch listener supervisor it throws and logs an error.
Checks whether the ranch connections can be found.
If not the upgrade will be canceled. This function runs twice because it is executed before
the “point of no return”, once when checking the relup and once when executing the relup.
It also tries to detect the websocket processes if the Phoenix.PubSub.PG2
pubsub
backend is used for phoenix websocket channels. It will not fail if that detection
is not possible, but a warning is printed
Returns the pids of the connections which are websocket connections for channels.
This detection works only if Phoenix.PubSub.PG2
is used as pubsub backend. If detection fails,
it returns :not_detected
. Knowing which processes of the known connections are websockets is useful
because they should be suspended during the hot code upgrade and resumed again afterwards.
If detection fails, websocket connections must be treated as “normal” http request connections.
Detection of websocket connections is not possible either by the phoenix api nor by the cowboy / ranch api.
Thats why this function takes the processes that are monitored by the Phoenix.PubSub.Local
process
and are a subset of the detected connections as websocket connections for channels. The lookup for
Phoenix.PubSub.Local
process is dones by searching the supervision tree of the application for:
`Phoenix.Endpoint` -> `Phoenix.PubSub.PG2` -> `Phoenix.PubSub.LocalSupervisor` -> [`Supervisor`](https://hexdocs.pm/elixir/Supervisor.html) -> `Phoenix.PubSub.Local`